xen/balloon: the balloon_lock is useless
Jeremy Fitzhardinge [Fri, 3 Sep 2010 06:11:17 +0000 (23:11 -0700)]
The balloon_lock is useless, since it protects nothing against nothing.

Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>

drivers/xen/balloon.c

index df26ee9..77b5dc3 100644 (file)
@@ -195,7 +195,7 @@ static unsigned long current_target(void)
 
 static int increase_reservation(unsigned long nr_pages)
 {
-       unsigned long  pfn, i, flags;
+       unsigned long  pfn, i;
        struct page   *page;
        long           rc;
        struct xen_memory_reservation reservation = {
@@ -207,8 +207,6 @@ static int increase_reservation(unsigned long nr_pages)
        if (nr_pages > ARRAY_SIZE(frame_list))
                nr_pages = ARRAY_SIZE(frame_list);
 
-       spin_lock_irqsave(&xen_reservation_lock, flags);
-
        page = balloon_first_page();
        for (i = 0; i < nr_pages; i++) {
                BUG_ON(page == NULL);
@@ -251,14 +249,12 @@ static int increase_reservation(unsigned long nr_pages)
        balloon_stats.current_pages += rc;
 
  out:
-       spin_unlock_irqrestore(&xen_reservation_lock, flags);
-
        return rc < 0 ? rc : rc != nr_pages;
 }
 
 static int decrease_reservation(unsigned long nr_pages)
 {
-       unsigned long  pfn, i, flags;
+       unsigned long  pfn, i;
        struct page   *page;
        int            need_sleep = 0;
        int ret;
@@ -296,8 +292,6 @@ static int decrease_reservation(unsigned long nr_pages)
        kmap_flush_unused();
        flush_tlb_all();
 
-       spin_lock_irqsave(&xen_reservation_lock, flags);
-
        /* No more mappings: invalidate P2M and add to balloon. */
        for (i = 0; i < nr_pages; i++) {
                pfn = mfn_to_pfn(frame_list[i]);
@@ -312,8 +306,6 @@ static int decrease_reservation(unsigned long nr_pages)
 
        balloon_stats.current_pages -= nr_pages;
 
-       spin_unlock_irqrestore(&xen_reservation_lock, flags);
-
        return need_sleep;
 }